Although I’m not in love with the stop-start feature, it’s on my 2018 F150 with the 3.5 ecoboost and I would like it to work. The feature doesn’t work like it should. I drive the truck 40-50 miles daily and it doesn’t work. A couple of weekends ago we drove it about 250 miles and just before we got home, it started working when we stopped for traffic signals. The next day it also worked ,but hasn’t since that day. With the dash feature on the stop- start it reads “Engine on due to vehicle charging”. I’ve had it at the dealership a couple of times and they can’t find what’s wrong with it. I’m going to take it back next week. I’m thinking that something is discharging the battery when it sits although it always starts. Anyone else have this problem? Thanks.

 

Yes, others have this issue.

 

My understanding is that everything has to be up to temp and that likely includes battery charge level I would think, in order for the stop start function to work. Battery seems ok but the system may think it's a little weak. The stop start function is going to use additional battery power. Not working is a self protection for the battery. Just a theory that it could be the battery charge level system.

personally, I dislike the stop start function. I've gotten into the habbit of turning it off each time I start the engine.

 

I wanted to let everyone know that this issue has finally been resolved. One day this week the truck didn’t want to start so I had the dealer check the battery and, sure enough, it was bad. I got it replaced under warranty so once it’s fully charged the stop/start should be functioning again. The dealer has reset the computer about three times now with no positive results. Why didn’t they check the battery months ago? At least I have a new battery on an almost 3year old truck.

 

Problem isn't with the stop start function, the BMS controls its use whenever it senses a power load on the system beyond what it can handle to preserve power from the alternator and battery. Your owner's manual outlines what the BMS will shut off to do that. The start stop function is one of them. Your battery may just be a little low on charge from use of accessories and needs a good charger maintainer to bring it back up to full charge. It is likely sitting around 60% charged. Measure the voltage and report back. Reccomend getting the CTEK 5.0 charger. I use mine periodically to replenish a full 100% charge. It will make the battery last longer.

 

Resetting the BMS is pointless if a battery's state of charge is low to begin with. Why? Because the BMS will control to the state of charge it measures at that time even though the battery is good and can still accept a full charge. Ideally, you want to reset the BMS when a battery is fully charged be it new or 3 years old.

The point is: Even a new battery can be at a state of charge less than 100%. I hope they insured that before making the reset.